Many infectious diseases may be transmitted through an accidental puncture by a contaminated hypodermic needle. The potential for this problem is very high when handling disposable hypodermic needles since they are not sterilized after use and often are not disposed of in a manner which will reduce the likelihood of accidental puncture. Since the advent of Acquired Immune Deficiency Syndrome (AIDS), increasing concern has developed on the subject of the safety of hypodermic needles.
Many designs have been developed for shielding the pointed end of a disposable needle. Some of the designs are automatic and thus do not require manual manipulation. In handling disposable needles, it is the manual capping of a hypodermic needle that poses such a risk since the more a person has to manipulate a needle point, the higher the risk of accidental injury.
In that regard, any design requiring a manual recapping operation presents some risk of an accidental puncture, and moreover, manual recapping of a needle is time consuming. In today's medical environment in which health care workers are already overworked and in short supply, the time spent in recapping a hypodermic needle can be much better utilized on other tasks. Considering the number of times hypodermic needles are used, the total time spent on recapping hypodermic needles is quite significant. In a sense, that represents an inefficient use of resources. Examples of prior designs that required manual manipulation are described in U.S. Pat. Nos. 3,406,687; 4,681,567; 4,747,837 and 4,801,295.
Past automatic designs, on the other hand, are generally complicated, costly to manufacture, and/or prone to defects. As a general rule, the more complex the design, the more expensive the cost of manufacturing, and the more likely it is that the construction will malfunction. An example of an automatic design is described in U.S. Pat. No. 4,775,369.
U.S. Pat. No. 4,973,317 provides a protective construction for a medical needle, particularly a hypodermic needle, that is durable, simple in design and not prone to malfunction. The protective construction includes a sheath which circumscribes the needle in tight-fitting relationship and which has an end portion that penetrates a patient's tissue along with the needle point. The sheath has one or more barbs which interact with a patient's tissue such that extraction of the sheath from the patient is postponed to a time no earlier than extraction of the needle point. In that manner, upon extraction of the sheath from the subject, the needle point is automatically covered by the sheath, thus providing protection against accidental puncture by the needle point after use. Furthermore, such interaction is used to provide the movement necessary to cover the needle point. This patent also discloses the use of a sleeve arrangement which provides a seat for assuring that the sheath follows the needle pointed end in penetrating the patient's tissue. Interaction between the sheath and sleeve locks the sheath in position covering the needle pointed end.
The barbs of the device of U.S. Pat. No. 4,973,317 can, however, be irritating or painful to some patients and/or some medical practitioners may feel that it may cause such irritation and elect not to make use of such a protective construction. Also, production of protective constructions which include such barbs can be difficult and/or expensive.
Some of the above identified problems of automatic type hypodermic needle protective designs are also applicable to those designs requiring manual manipulation. There is much room for improvement.
The present invention is directed to overcoming one or more of the problems as set forth above.